Introduction to PCB design of H-bridge for Motor control

If you are interested in robotics controls with h-bridge circuit, then one should make a PCB for h-bridge because they are useful and reusable.That is why I decided to make a PCB layout board for h-bridge circuit which can be controlled via two pins which is to be connected to the microcontroller like Arduino or ESP32 boards. For four motors the same PCB can be used by PCB penalization process. Here I will use Proteus professional PCB design tool called ARES. The final PCB design layout is as shown.

Schematic

The first step is the schematic of the h-bridge with the inputs and outputs. Here 12V power supply for motor is used and two inputs for controlling the motor and two outputs for the motor terminals.

This the same h-bridge for motor speed and direction control which was explained in the guide BJT H-bridge Circuit Operation. 

I have placed three 2 pin headers to connect the power supply for the motor (J1), the inputs controls(J3) and outputs(J2) as shown below.

One has to check and verify that all the schematic components have the proper PCB footprint. In my case I used TO-92 footprint for the transistors that I had. 

PCB Design

Once the schematic is complete, one can then begin the PCB layout design. 

Component Placement

In proteus ARES pcb design software, we have to create the pcb board outline in yellow color first as shown below.

Then I started placing the six transistors in bridge topology inside the pcb board outline as shown below.

PCB Trace Routing

After the completion of component placement onto the pcb board, the next step is to route the PCB traces. I have used intentionally 50 mils for all the trace width, which may not be the best practice but since this pcb board will be fabricated at home, and since during the PCB etching process, because of sometimes bad printer toner transfer, the traces may get damaged. By using wider PCB trace the chances of making mistake during the toner transfer to the pcb copper clad. 

Below is the completely routed PCB board.

Ground Plane

One can use this routed PCB layout but it is better to add ground plane. After ground plane is poured the complete PCB design board for H-bridge motor driver with BJT transistors for controlling motor is complete. This is as shown below.

That's it. This is how I designed a diy h-bridge PCB board for robotics motor control. If are new to PCB design check out our beginner guide to PCB component placement and routing,

The following is a complete PCB design tutorial video which shows all the steps involved and explained above. 

This h-bridge circuit uses BJT transistors but MOSFET are better suited for handling power and current. Regardless of BJT or MOSFET, the same process can be used to make PCB layout for H-bridge with P-channel and N-channel MOSFETs.